Among the earliest devices fashioned by man to measure the passage of time is that commonly known as the hour glass or sandglass timer. From earliest recorded history these hour glass timers have characteristically included a pair of chambers connected by a necked opening between the chambers to allow the passage of granules from one chamber to the next whenever the timer was inverted. For centuries these timers have been employed whenever a relatively brief passage of time was sought to be measured, and the user of the timer was free to watch the passage of the last granule from one chamber to the other herald the passage of time for which the timer was designed. The parameters of design for this type of timer are relatively simple and include such factors as the size and nature of the granule passing through the opening; the size of the opening and finally, the nature of the cross-sectional opening between the chambers. In all cases known, each span of time sought to be measured required an individually designed timer. Until recently, granule timers of the type being described here required that the user of the timer note visually the passage of the last granule in order to determine the moment the passage of time sought to be measured had lapsed.
The only known sandglass that provides a visual external indication of the passage of time is that patented by David Spivak in U.S. Pat. No. 3,707,842, in which Spivak provides what he terms as an electric signal sandglass. The Spivak electric signal sandglass is shown in the two embodiments of FIG. 1 and FIG. 2. In the FIG. 1 embodiment the classic sandglass described earlier is equiped with a pair of electrically conductive caps 18, 19 which slide on a guide 17 between two positions. The sandglass has a pair of chambers 12 and 13 which include respectively pairs of electrodes 24, 25 and 29, 30, which electrodes are electrical switch contacts for an indication circuit remote from the timer. Whenever the sandglass is inverted, one of the caps 18, 19 rides on the sand granules captured in the chambers 12 and 13 between the caps 18, 19 until the sand 16 has passed through the opening 15 in the neck 14, and the cap then completes the indication circuit noted above. In FIG. 2 of Spivak, a pair of balls 46, 47 carried on a guide 17 fulfills the same function as the caps 18, 19 described in respect of FIG. 1.
The invention to be described more fully hereinafter distinguishes of Spivak in that the granules in the timer are electrically conductive and further the timer is capable of providing a number of preselected time measurements and independently signal the passage of the preselected time.
The subject invention to be described would have particular utility in a timer in my now issued U.S. Pat. No. 4,326,709, Ser. No. 06/101,777, titled Fishing for Cards Game where the players taking turns have their playing time controlled by a simple and inexpensive timer that requires a number of different elapsed times be offered to each player depending upon the skill of the player.